Multible Activities in Android

In android each activity should have one clear functionality and if you need to make something that fundamentaly does something else then you should create new activity. but if to be implemented functionality is somehow similar but doesn't fit in this view. You should consider switching between views, or using tab pane.

links:

http://developer.android.com/reference/android/app/Activity.html

http://stackoverflow.com/questions/2072244/android-what-is-better-multiple-activities-or-switching-views-manually

http://www.warriorpoint.com/blog/2009/05/24/android-how-to-switch-between-activities/

http://www.mathcs.org/java/android/multi_acts.html